[libvirt] [PATCH v3 0/2] vbox: address thread-safety issues

[Dawid Zamirski]

This patch series solves vbox driver thread-safety issues where
libvird process would segfault when there was more than one concurrent
vbox connection. The reason for the segfault was because the original
implementation called pfnComInitialize/Unintialize on each
virConnectOpen/Close calls which were setting pointers to ISession and
IVirtualBox instances that were held by the global g_pVBoxGlobalData.
This caused new connection to overwrite the pointer created by the
prior connection.

Changes since v2 to address feedback in [1]:

* call uninitialize when vboxSdkInitialize or vboxExtractVersion fails.
* make sure to set the global vbox_driver pointer to NULL after 
  virObjectUnref releases last  reference, to avoid segfaults when
  VBOX_RELEASE is called in unintialize call.
* tested all possible failure paths to make sure libvirtd does not
  crash, that is, vboxSdkInitialize has 4 code paths that can possibly
  return -1 and made sure all of them are safely handled.
* fixed "unintilalize" typos in code comments and commit messages.

In other words, the change boils down to:

if (vboxSdkInitialize() < 0 || vboxExtractVersion() < 0) {
    gVBoxAPI.UPFN.Uninitialize(vbox_driver); // call uninit on failure
    /* make sure to clear the pointer when last reference was released */
    if (!virObjectUnref(vbox_driver))
        vbox_driver = NULL; // make sure this is NULL

    virMutexUnlock(&vbox_driver_lock);

    return NULL;
}

[1] https://www.redhat.com/archives/libvir-list/2016-November/msg01132.html

Dawid Zamirski (2):
  vbox: change how vbox API is initialized.
  vbox: get rid of g_pVBoxGlobalData

 src/vbox/vbox_common.c        | 565 +++++++++++++++++++++++-------------------
 src/vbox/vbox_common.h        |   2 +-
 src/vbox/vbox_driver.c        |   1 +
 src/vbox/vbox_network.c       |  24 +-
 src/vbox/vbox_storage.c       |  20 +-
 src/vbox/vbox_tmpl.c          | 434 ++++++++++++++++----------------
 src/vbox/vbox_uniformed_api.h | 110 ++++----
 7 files changed, 616 insertions(+), 540 deletions(-)

-- 
2.9.3